Geographical Location:
Southern prairies of Canada and US northern high plains, centered around Medicine Hat, Alberta
Case Timeframe:
11-13 November 2003
Phenomena of Interest:
Alberta Clipper and the associated snowfall and blowing snow
Forecasting Challenges:
This case study focuses on a snow and blowing snow event in the Canadian prairies and US northern high plains on 11-13 November 2003. The key aim of this module is to step through the forecast process during an Alberta Clipper event from the perspective of a forecaster with the Meteorological Service of Canada. This involves consideration of various observations and model guidance, identification of potential areas of snowfall and blowing snow, nowcasting snowfall development and termination, and considering and providing nowcast updates throughout.
An Alberta Clipper is a low pressure system that is typically fast-moving and originates in western Canada. It usually moves south and east across the prairies towards, and sometimes across, the Great Lakes region. It is often associated with a narrow but significant band (or bands) of snowfall, and occurs most often and is most intense during the cold season. These systems represent a winter forecasting challenge as they are often difficult to predict more than 12 hours ahead of time, and they can shut down highways with heavy blowing/drifting snow. Severely restricted visibility, slowdowns in all transportation systems, and dangerously low wind chills are other public impacts.
This case is presented in three main parts: